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Northern Harrier
Circus hudsonius

Status: Lower risk

Population Trend: Stable.

Other Names: American Harrier, Marsh Hawk, North American Harrier.

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Circus hudsonius
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Distribution: Nearctic/Neotropical. Breeds from northern ALASKA and northern CANADA (North West Territories, Quebec, Nova Scotia) south to northern MEXICO (Baja California), northern Texas, central Illinois, and east to New England and the mid-Atlantic UNITED STATES; winters from southern ALASKA south through the UNITED STATES and MESOAMERICA to PANAMA and less commonly through the ANTILLES to northern VENEZUELA and COLOMBIA. more....

Subspecies: Monotypic.

Taxonomy: Recently separated from the Hen Harrier of Eurasia, C. cyaneus, based on an analysis of nucleotide sequences of the mitochondrial cytochrome b gene by Wink et al. (1998), who were followed by Simmons (2000) and Ferguson-Lees and Christie (2001). Wink and Sauer-Gürth (2000, 2004) confirmed a close relationship between this species, C. cyaneus, C. cinereus, C. macrourus, and C. maurus, based on cytochrome b evidence.

Movements: Partial migrant (Bildstein 2006). more....

Habitat and Habits: Occurs in a wide variety of open habitats, including wet freshwater or alkaline marshes, prairie, grasslands, old pastures, and cultivated areas. In winter, it may occupy communal roosts containing as many as 80-90 birds in areas of high prey density (Weller 1955, Littlefield 1970, Mumford and Danner 1974). more....

Food and Feeding Behavior: Voles and other small rodents are the principal prey in the northern Great Plains (Hamerstrom 1986, Johnson et al. 1998), but this species also feeds on other small mammals, birds, reptiles, frogs, fish, arthropods, and carrion (Errington 1933, Selleck and Glading 1943, MacWhirter and Bildstein 1996). Small mammals and birds form the bulk of the diet during the breeding season, but wintering birds take a higher frequency of mammals, probably because fewer songbirds are available then (Munoff 1963). Like other harriers, this species hunts by quartering low over the ground, often circling over potential prey before plunging to the ground to capture it. more....

Breeding: Nesting begins in middle to late spring. Nests are mats of grasses and weeds placed on the ground in open fields or grasslands, or over shallow water on platforms of vegetation in stands of cattails or other emergent vegetation, usually in undisturbed areas (Saunders 1913, Sealy 1967, MacWhirter and Bildstein 1996). Only the female builds the nest, but the male may deliver nesting material. The clutch size is from 3-6 eggs, and the incbuation period is 23-26 days. Females generally perform all of the incubation. Males have rarely been observed on the nest (Hamerstrom 1969), but they provide all of the food during incubation and the early nestling period. Male nestlings fledge at 31-34 days and females at 35-38 days (Scharf and Balfour 1971). Only one brood is produced per season, but renesting may occur if a nest is lost during egg laying (Bildstein and Gollop 1988). more....

Conservation: Widespread and relatively common in large portions of its range. However, it is locally scarce in many areas and is listed as a Species of Special Concern by the U.S. Fish and Wildlife Service and has special status in several states. The recent conservation assessment by Slater and Rock (2005) provides an excellent overview of the biology and conservation status of this species. The principal threat to this species is habitat destruction, mainly through the draining of wetlands and conversion of agricultural areas to monocultures. Shooting and pesticide effects are likely less serious threats than they were in the past. Regarded as a species of Least Concern by BirdLife International (2007), where it is included as a subspecies of the Hen Harrier, C. cyaneus. more....

Important References: 
Bent, A.C. 1937. Life histories of North American birds of prey. Order
  Falconiformes (Part 1). U.S. National Museum Bulletin 167.
Bildstein, K.L., and J.B. Gollop. 1988. Northern Harrier. Pp. 251-303 in
  R.S. Palmer (ed.), Handbook of North American birds. Vol. 4. Diurnal
  raptors. Yale University Press, New Haven, CT.
Farmer, C.J., L.J. Goodrich, E. Ruelas Inzunzas, and J.P. Smith. 2007.
  Conservation status of North American raptors. Conservation status report:
  Northern Harrier. http://hawkmountain.org/media/harrierCSR_June07.pdf.
Ferguson-Lees, J., and D.A. Christie. 2001. Raptors of the world. Houghton
  Mifflin, Boston, MA.
Hamerstrom, F. 1986. Harrier, hawk of the marshes: the hawk that is ruled
  by a mouse. Smithsonian Institution Press, Washngton, D.C.
MacWhirter, R.B., and K.L. Bildstein. 1996. Northern Harrier (Circus
). Birds of North America no. 210. Academy of Natural Sciences,
  Philadelphia, PA, and American Ornithologists' Union, Washington, D.C.
Orta, J. 1994. Hen Harrier. P. 139 in del Hoyo, J., A. Elliott, and J.
  Sargatal (eds). Handbook of birds of the world. Vol. 2. New World vultures
  to guineafowl. Lynx Edicions, Barcelona, Spain.
Simmons, R. 2000. Harriers of the world: their behaviour and ecology.
  Oxford University Press, Oxford, UK.
Slater, G.L., and C. Rock. 2005. Northern Harrier (Circus cyaneus): a
  technical conservation assessment. USDA Forest Service, Rocky Mountain
  Region, Species Conservation Project. 38 pp.

Sites of Interest:
Northern Harrier photos.

Bildstein, Keith
Goodrich, Laurie
McIntyre, Carol
Preston, Charles
Rodríguez Santana, Freddy
Scott, Don
Simmons, Rob
Smith, Brian
Watts, Bryan

Last modified: 3/15/2010

Recommended Citation: Global Raptor Information Network. 2021. Species account: Northern Harrier Circus hudsonius. Downloaded from http://www.globalraptors.org on 9 Dec. 2021

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